Example 4-9. Specifying the execution context for a wrapped function

var person = {
	name: 'Marie',
	introNodeStyle: function (callback) {
		var err = null;
		callback(err, 'My name is ' + this.name);
	}
};

var wrapper = Bluebird.promisify(person.introNodeStyle);
	wrapper().then(function (greeting) {
	console.log('promisify without second argument: ' + greeting);
});

var wrapperWithPersonArg = Bluebird.promisify(person.introNodeStyle, person);
	wrapperWithPersonArg().then(function (greeting) {
	console.log('promisify with a context argument: ' + greeting);
});

var wrapperWithBind = Bluebird.promisify(person.introNodeStyle.bind(person));
	wrapperWithBind().then(function (greeting) {
	console.log('promisify using function.bind: ' + greeting);
});

// Console output:
// promisify without second argument: My name is
// promisify with a context argument: My name is Marie
// promisify using function.bind: My name is Marie